Although Hagrid was almost fifty years older than Harry and the others, he never really occupied the role of an elder in their relationship. More often, he was a friend-and a "little" friend who might need special looking after from time to time.
"Little" certainly did not refer to his age, nor, obviously, his size. It meant that Hagrid's thinking was often far too innocent and naïve. To put it kindly, he had a childlike heart. To put it unkindly, he had a screw loose.
Harry and Ron both believed that Hagrid would never encourage an Acromantula to eat people, but they feared he was equally incapable of stopping it and its offspring from doing so.
With that in mind, Harry felt no guilt whatsoever about killing the Acromantula and wiping out every last one of its descendants along with it.
"In that case, we can't really give this to Professor Slughorn directly for the time being." Harry looked at Aragog, whom he had beheaded with a single Sword Beam Spell and who was now thoroughly dead, and spoke with some regret.
"Then just collect the venom first," Tris said, unconcerned. "We can deal with it once this has blown over. It shouldn't spoil that easily. If it comes to it, we can use magic to preserve it."
As he spoke, he took out several test tubes, porcelain bottles, and similar containers.
"That's all we can do." Harry thought it over and nodded, taking a porcelain bottle to collect the Acromantula's venom-he had done similar work in Potions Class.
The spider they had used then had only been an ordinary magical spider the size of a fist, but the same principles applied.
Ron wanted to help, but found the task rather revolting. He could only ask hesitantly, "Harry, should we